1. Field of the Invention
The present invention relates to a power connection structure of a driver IC (integrated circuit) chip, and more particularly, to a power connection structure of a driver IC chip, in which routing patterns in a driver IC chip are disposed parallel to LOG (line-on-glass) type lines to connect power terminal units disposed on both ends of the driver IC chip, thereby simplifying wiring lines and reducing line resistance.
2. Description of the Related Art
A liquid crystal display (LCD) means a device which uses a characteristic that an aligned state of liquid crystal molecules is changed depending upon an applied voltage and image data is displayed by passing light through liquid crystals. Recently, a most actively used device among liquid crystal displays is a thin film transistor type liquid crystal display (TFT-LCD) which is made by using a silicon IC manufacturing technology.
FIG. 1 is a diagram schematically illustrating the structure of a conventional liquid crystal display.
The TFT-LCD includes a liquid crystal display panel 30 in which a thin film transistor array substrate and a color filter substrate are attached to each other with a predetermined space defined therebetween and liquid crystals are disposed in the predetermined space, and driving circuits for driving the liquid crystal display panel 30.
The driving circuits includes a gate driver IC 40 configured to sequentially apply scanning signals to gate lines in each frame, a source driver IC 20 configured to drive source lines in correspondence to the scanning signals from the gate driver IC, a timing controller 10 configured to control the gate driver IC 40 and the source driver IC 20 and output pixel data, and a power supply unit (not shown) configured to supply various driving voltages to be used in a liquid crystal display device.
In general, methods for connecting the driver ICs with the liquid crystal panel include a TAB (tape automated bonding) type in which the driver ICs are mounted to a thin flexible film made of a polymer substance, that is, a TCP (tape carrier package) and the film is connected with the liquid crystal panel to electrically connect the driver ICs with the liquid crystal panel, and a COG (chip-on-glass) type in which the driver ICs are directly mounted to the glass substrate of the liquid crystal panel by using bumps and are thereby connected to the liquid crystal panel.
In the COG type, a method is used, in which the output electrodes of the driver ICs are directly connected to pads to integrate the substrate and the driver ICs. In the COG type, when performing a process for bonding the bumps and the pads, the bumps and the pads are bonded with each other by conductive particles which are disposed between the bumps and the pads.
In the COG type, the driver IC chips mounted to the liquid crystal panel are connected with one another in a line-on-glass (LOG) type in which signal lines are directly disposed on the thin film transistor array substrate, and are supplied with control signals and the driving voltages from the timing controller and the power supply unit.
FIG. 2 is a diagram illustrating a power connection structure of a driver IC chip which is mounted in a COG type generally known in the art.
Referring to FIG. 2, in the case of a driver IC chip, it is the norm that the driver IC chip has a rectangular shape in which a transverse length is substantially longer than a longitudinal length due to the characteristics of a liquid crystal display application. If a power source is disposed only in one side of the driver IC chip, since signals may become weak on the other side with no power source, operational problems may be caused.
Accordingly, in a driver IC chip 200 which is mounted in the conventional COG type, internal circuits 230 are centrally disposed, and power terminal units 210 and 220 are respectively disposed on both sides of the driver IC chip, so that operational problems due to signal damping can be solved.
However, because the power sources disposed on both sides of the driver IC chip should be connected with each other by separate connection lines on flexible printed circuits (FPCs), input/output wiring lines become complicated on the FPCs. Also, since the wiring lines are added, economy may deteriorate.
Moreover, in the conventional COG mounting type, a disadvantage is caused in that a voltage drop is likely to occur due to inherent resistance of a signal or power supply line composed of a metal line.